Page 8
IMPORTANT
For safety, connect a shutĆoff valve between the
manometer and the gas tap to permit shut off of
gas pressure to the manometer.
Operating Pressure (outlet) in. W.C.
TABLE 4
GAS VALVE REGULATION
3.5 +0 -0.3
Natural
L.P.
9.5 + 0.5
Unit (Fuel)
The gas valve is factory set and should not require adjustĆ
ment. All gas valves are factory regulated. See table 4.
Manifold Adjustment Procedure:
1- Connect a test gauge to outlet pressure tap on gas
valve. Start unit and allow 5 minutes for unit to reach
steady state.
2- While waiting for the unit to stabilize, notice the flame.
Flame should be stable and should not lift from burner.
Natural gas should burn blue. L.P. gas should burn
mostly blue with some orange streaks.
3- After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to values given in
table 4.
NOTE-Shut unit off and remove manometer as soon as
an accurate reading has been obtained. Take care to
replace pressure tap plug.
F- Proper Gas Flow
To check for proper gas flow to combustion chamber, deterĆ
mine Btuh input from unit rating plate or table or the specifiĆ
cations tables on pages 1 and 2. Divide input rating by Btuh
per cubic foot of available gas. Result is the number of cubic
feet per hour required. Determine flow of gas through gas
meter for two minutes. Multiply by 30 to get hourly flow of
gas to burner.
NOTE- To obtain accurate reading, shut off all other
gas appliances connected to meter.
G-High Altitude Derate
C.G.A. certified units used in high altitude applications are
factory equipped with modifications that eliminate the
need for manifold pressure adjustment to obtain proper
heat input. Check the unit rating plate to make sure unit is a
high altitude unit.
A.G.A. certified units must be derated when installed at an
elevation of 2,000 ft. (610 m) or more above sea level.
Tables 5 and 6 show the derated manifold pressure for
high altitude operation with both natural and LP/Propane
gas. Operating this appliance at the manifold pressure
specified on the tables will ensure proper unit heat input at
high altitude. Consult your gas utility for the local natural
gas heating value.
2.25" wc
Altitude
*Heating Value (Btu/Ft
#
)
(Ft.)
900
950
1000
1050
1100
0
1000
2000
3000
4000
5000
6000
4.32" wc
4.32" wc
3.65" wc
3.35" wc
3.05" wc
2.77" wc
2.50" wc
3.88" wc
3.88" wc
3.30" wc
3.00" wc
2.75" wc
2.48" wc
3.50" wc
3.50" wc
2.95" wc
2.70" wc
2.45" wc
2.25" wc
3.17" wc
3.17" wc
2.70" wc
2.45" wc
2.25" wc
2.89" wc
2.89" wc
2.45" wc
2.25" wc
HIGH ALTITUDE MANIFOLD PRESSURE
DERATE FOR NATURAL GAS UNITS
*Heating value based on atmospheric pressure of 30" mercury and
temperature of 60
°
F (16
°
C).
TABLE 5
_ _
_ _
_ _
_ _
_ _
_ _
NOTE-This is the only permissible field derate for this
appliance.
ALTITUDE
(Ft.)
MANIFOLD
PRESSURE
HIGH ALTITUDE MANIFOLD PRESSURE
DERATE FOR LP/PROPANE GAS UNITS
0
1000 2000 3000 4000 5000 6000
9.5"
w.c.
8.0"
w.c.
7.2"
w.c.
6.5"
w.c.
5.9"
w.c.
5.3"
w.c.
TABLE 6
9.5"
w.c.
IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
H-Flame Signal
A 50 microamp DC meter is needed to check the flame sigĆ
nal on the primary ignition control.
Flame (microamp) signal is an electrical current which
passes from the ignition control through the sensor elecĆ
trode during unit operation. Current passes from the senĆ
sor through the flame to ground to complete a safety cirĆ
cuit.
To Measure Flame Signal:
1- Place meter in series between ignition control and
sensor wire. Connect the positive (+) lead of meter to
the ignition control sensor connection and the negaĆ
tive (-) lead of the meter to the sensor wire. See figure
14.
2- Set thermostat for a heating demand and check flame
signal with unit operating. For G17 series, a reading of
1 to 5 microamps DC should occur.
